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March I7, 1964 J; A. FINAN METHOD 0F PREPARING A BUILT-UP ROOF' Filed March 5l, 1959 -v\\.\\\w\,\.\v.\

.vn .2.5.22 naozzznt m. .2.5.22 mnoatn ONJSMPS msooh INVENTOR JAMES A.FINAN AT ORNEY United States Patent O 3,125,479 METHOD F PREPARING A HUET-UP RGOF James A. Finan, Glenolden, Pa., assigner to Ailied Chemical Corporation, N ew York, N.Y., a corporation of New York Filed Mar. 31, 1959, Ser. No. 803,304 3 Claims. (Cl. 156-300) This invention relates to built-up roofs and more particularly to a built-up roof constructed with surface-sized insulation boards.

Construction of built-up roofs is generally carried out by bonding Waterprooiing layers of felt saturated with bituminous material, e.g. pitch or asphalt to each other and to a layer of thermal insulation comprising juxtaposed rigid insulation boards, e.g. cellulose iiber insulation boards by moppings of the liquefied bituminous material. It is necessary that the insulation boards be bonded to the felt by a uniform and effective bond to insure that water does not pass into the insulation board with attendant damaging of the same. The thermal insulation layer is supported by the roof deck or other supporting structure. A serious difficulty encountered in constructing such built-up roofs is that the porous insulation boards absorb excessive amounts of the adhesive bituminous material applied thereto leaving an inadequate quantity of such bituminous material on the board outer surfaces to obtain good bonding between the boards and a subsequently applied layer of rooling felt. Consequently, additional moppings of the bituminous material have to be applied to the board outer surfaces to provide an adhesive layer for bonding the felt to the boards, such additional moppings being undesirable due to increased material and labor costs. Further, the normal thermal insulating value or properties of the boards is considerably reduced due to the considerable absorption or diffusion of bituminous material into the interior of the boards, only that portion of the boards not containing the absorbed bituminous material exhibiting satisfactory insulating properties. It has further been found that diffusion and absoiption of the bituminous layer continues on prolonged exposure of the roof to the atmosphere with further deterioration of the thermal insulation value of the rigid board and with loss of bonding eliect.

One object of this invention is to provide a built-up roof structure having improved thermal insulating properties.

Another object is to provide a built-up roof structure which will retain its high thermal insulating properties under conditions of prolonged exposure.

Another object is to provide a built-up roof structure having an improved bond while employing a materially reduced amount of adhesive bituminous material between the insulation boards and overlying rooting felt.

An additional object is to provide a built-up roof structure which will retain excellent bonding under conditions of prolonged exposure.

A further object is to provide a built-up roof structure of improved thermal insulation properties and stronger bond with the elimination of additional moppings of adhesive bituminous material normally required in built-up roof construction.

A still further object is to provide a built-up roof structure of improved thermal insulating properties and stronger bond at lower cost.

Additional objects and advantages will be apparent as the invention is hereinafter described in detail.

In accordance with the present invention, the built-up roof structure comprises a supporting structure, a layer of thermal insulation material comprising juxtaposed rigid normally porous roof insulation boards on the supporting Value of the boards by material diiiusion of the bituminous material into the interior of the boards, and a superposed layer of rooting felt bonded to the boards by the adhesive bituminous material retained on the outer surfaces of the boards due to the sizing material.

In construction of the built-up roof structure, a layer of steep asphalt having thickness of typically about C115-0.08 inch is preferably applied over the supporting structure or roof deck, and then a continuous vapor barrier film is applied over the steep asphalt. The vapor barrier film, typically of 4 mils thickness, can be formed of water vapor impervious or substantially impervious material, eg. aluminum, cellulose acetate, polyethylene, a plasticized polyvinyl chloride composition, polyester iilm or rubberlike materials. A plurality of the surface-sized roof insulation boards are laid or installed over the vapor barrier film in juxtaposition to one another to form the thermal insulation layer, the boards characterized by being rig'id, normally porous, having typical thickness of about 1/2-2 inches and having high thermal insulation value per se. Thereafter an adhesive layer of heat-liqueiied bituminous material, eg. asphalt or coal-tar pitch is applied over the outer surfaces of the surface-sized boards. In the prior art construction of the roof, on application of the adhesive layer of bituminous material to the outer surfaces of the unsized thermal insulation boards, as much as 70% and higher of the bituminous material was absorbed or disappeared into the interior of the boards of the insulation layer. Such considerable adhesive absorption into the boards is disadvantageous for the reasons that it considerably reduces the normal thermal insulating value of the boards, and results in loss of adhesiveness and increased material and labor costs.

YIn the roof construction of the present invention, this disadvantageous considerable absorption of bituminous 'material isV avoided by applying, prior to adhesive bituminous application, sizing material to surfaces of the boards intended to be outer surfaces thereof in the thermal insulation layer of the built-up roof structure. The sizing passes into and iills surface pores and pores adjacent the surfaces of the boards thereby preventing or blocking passage of the bituminous material into these pores. Application of sizing is by brushing, spraying or other suitable means and is preferably carried out before installation of the boards on the supporting structure, although it may be effected after installation. When application is before installation of the boards, the sizing is applied either to wet board entering or dry board leaving the board drying machine. The sizing material is preferably applied only to that surface of the board or boards intended to be the board outer surface or surfaces in the built-up roof structure. While the sizing material may also be applied to the inner or lower surface 0f the board or boards, if desired, in addition to application to the outer surface, no advantage is attained thereby from the standpoint of inhibiting absorption of the adhesive bituminous material and the insulating value of the board is reduced with the filling of more of the pores.

Sizing material applied is preferably an aqeous sizing material comprising about 2-10% by weight of the sizing material, e.g. bentonite clay, pearl starch or soya bean liour, and water. Aqueous sizing material containing by weight, about 5 %-10% of bentonite clay dispersed in about %-90% water is preferred among such sizing materials. Application of the aqueous sizing material is preferably at a rate of about 7-8 pounds per 100 square feet of the board. Examples of other sizing materials which can be employed are dextrin, gun tragacanth, albumin gel and casein, preferably when combined with water.

By reason of the surface pores of the insulation boards being filled with the sizing material, from about 90%- 100% of the applied bituminous material is retained on the outer surfaces of the boards for bonding superposed roofing felt to the boards. Consequently, application is not required of additional layers of the bituminous material to the board outer surfaces to compensate for absorbed bituminous material with attendant increased material and labor costs. Further, the normal thermal insulating value is maintained at a high level by the absence of material diffusion of the bituminous material into the interior of the boards. The applied sizing material passes into the insulation board and fills surface pores and pores adiacent the surface of the board when of 1/2 inch thickness a typical distance of about 0.015 inch, or about 3% of the board thickness from the outer or upper surface of the board to the lower surface thereof. Thereafter a layer of bituminous materialsaturated felt, e.g. felt saturated with tar or asphalt is applied to the bituminous layer while the bituminous layer is in a soft and tacky condition. Application of the adhesive bituminous layer and the bituminous-saturated felt is then preferably repeated as described until a plurality of alternate superposed layers of the bituminous material and saturated felt are applied over the first applied saturated felt layer. Typically four layers of bituminous material and three layers of bituminous material-saturated felt are applied over the insulating boards, each bituminous layer and each felt layer having typical thickness of about 0.05-0.08 inch and 0.02-0.04 inch respectively. Coarse mineral or aggregate particles, e.g. slag particles are preferably partially embedded in the outer surface of the outermost bituminous layer.

Insulation boards surface-sized in accordance with the invention for the roof construction are of wood, bagasse, wood pulp, iiax straw or asbestos fibers.

In the drawing:

The figure is a transverse section through a built-up roof of the present invention.

It will be readily apparent upon examination of the considerable improvement provided by the surface-sized insulation board of the present invention over the nonsurface sized insulation boards of the prior art with respect retention of adhesive bituminous material on the board outer surface. Insulation board was surface-sized in accordance with the present invention, followed by mopping application of coal-tar pitch at temperature of about 350 F. to the sized surface of the board and compared with insulation boards which were not surfacesized but were mopped with the coal-tar pitch and at the same temperature used in mopping the surface-sized board, substantially identical quantities of pitch being applied to all the boards. Substantially no pitch absortion was shown by the invention surface-sized board, virtually all pitch being retained on the surface of this board providing an entirely adequate adhesive layer for excellent bonding of roofing felt to the board. On the contrary, in the non-surface sized boards, a major portion of the pitch was absorbed by the boards leaving an inadequate portion of adhesive on the surfaces of each of these boards to provide good bonding of the roofing felt to the boards. Further, the absorbed pitch robs the boards of insulating value. When the pitch was deliberately overheated to 425 F. prior to application to these boards, a particularly dificult and troublesome application temperature, there was still substantially no absorption of the pitch by the surface-sized board of this invention and an entirely adequate adhesive layer was retained on the board surface for bonding of the felt. However, the nonsurface sized boards each absorbed substantially all of i the pitch leaving substantially no pitch on the board surface for bonding of the felt.

With reference to the figure, a foundation or roof deck of concrete is designated at 1t). As shown, layer 11 of steep asphalt is located over slab lil, and vapor barrier film 12 is superposed on layer il. Cellulose fiber insulation board 13 has its outer surface 14 sized with the bentonite clay sizing material, the sizing material fill-f ing surface pores on the board outer surface 14 and alst filling the pores of the board in region 1S thereof adjacent outer surface 14 of the board. A thin adhesive layer of coal-tar pitch i6 is superposed on sized outer surface ld of insulation board i3, substantially all of the pitch being retained on outer surface 14 by reason of the sizing material and only a small amount of pitch being absorbed by the board. Thin layer 17 of tar-saturated rooting felt is bonded to surface-sized board I3 by means of pitch layer le. Additional superposed thin bonding layers of the coal-tar pitch are shown at 13, 19 and 2t! respectively, superposed thin layers of the tar-saturated roofing felt being designated at Zi and 22. Coarse particles 23 of slag are partially embedded in the outer surface of pitch layer ZG.

in general, it was found that unsized fibrous insulation board absorbed about 50-70% of coal-tar pitch or asphalt when built-up rooting comprising superposed alternate layers of pitch or asphalt and saturated roofing felt respectively was applied over the insulation board. On the contrary the surface-sized insulation board was found to retain about %-100% of the adhesive coal-tar pitch or asphalt on its outer surface when the built-up rooting was applied thereto.

Although certain preferred embodiments of the invention have been disclosed for purpose of illustration, it will be evident that Various changes and modifications may be made therein without departing from the scope and spirit of the invention.

What is claimed is:

l. A method of preparing a built-up roof structure which comprises applying an aqueous sizing material to surfaces of rigid normally porous insulation boards intended to be board outer surfaces in the built-up roof structre, laying over a supporting structure the surfacesized insulation boards in juxtaposition to one another to form a layer of thermal insulation thereon, the pores in the interior of the boards adjacent the outer surfaces of the boards and the pores of the outer surfaces of the boards relative to the supporting structure filled with the sizing material, applying an adhesive layer of heat-liquetied bituminous material onto the sized outer surfaces of said boards, the bituminous material being retained on the outer surfaces of the boards due to the sizing material to avoid diminishing substantially the normal thermal insulating value of said boards by material diffusion of the bituminous material into the interior of the boards, and applying a layer of bituminous material-saturated felt onto the retained adhesive bituminous layer while said bituminous layer is in a soft and tacky condition.

2. A method of preparing a built-up roof which comprises applying an aqueous sizing material comprising about 2%-l0% by weight of the sizing material to only surfaces of rigid normally porous insulation boards intended to be board outer surfaces in the roof structure, laying over a roof deck the surface-sized insulation boards in juxtaposition to one another to form a layer of thermal insulation thereon, the pores in the interior of the boards adjacent the outer surfaces only of the boards and the pores of the outer surfaces only of the boards relative to the roof deck filled with the sizing material, applying an adhesive layer of heat-liquefied bituminous material onto the sized outer surfaces of said boards, from about 90%- of the bituminous material being retained on the outer surfaces of the boards due to the sizing material to avoid diminishing substantially the normal thermal insulating value of said boards by material diffusion of bituminous material into the interior of the boards, applying a layer of bituminous material-saturated felt onto the retained adhesive bituminous layer while said bituminous layer is in a soft and tacky condition, and repeating the steps of applying the adhesive bituminous layer and then the bituminous-saturated felt as aforesaid until a plurality of alternate superposed layers of bituminous material and bituminous material-saturated felt are applied.

3. A method of preparing a built-up roof which comprises applying an aqueous sizing material comprising, by Weight, about 5%-10% bentonite clay dispersed in about 95 7a-90% Water at an application rate of about 7-8 pounds per 100 square feet of board to only surfaces of rigid normally porous cellulose fiber insulation boards intended to be board outer surfaces in the roof structure, laying over a roof deck the surface-sized insulation boards in juxtaposition to one another to form a layer of thermal insulation thereon, the pores inthe interior of the boards adjacent the outer surfaces only of the boards and the pores of the outer surfaces only of the boards relative to the roof deck filled with sizing material, applying an adhesive layer of heat-liquefied bituminous material onto the sized outer surfaces of said boards, from about 90%- 100% of the bituminous material being retained on the outer surfaces of the boards due to the sizing material to avoid diminishing substantially the normal thermal insulating value of said boards by material diffusion of the bituminous material into the interior of the boards, applying a layer of bituminous material-saturated felt onto the retained bituminous layer While said bituminous layer is in a soft and tacky condition, and repeating the steps of applying the adhesive bituminous layer and then the bituminous material-saturated felt as aforesaid until a plurality of alternate superposed layers of bituminous material and bituminous material-saturated felt are applied.

References Cited in the tile of this patent UNITED STATES PATENTS 

3. A METHOD OF PREPARING A BUILT-UP ROOF WHICH COMPRISES APPLYING AN AQUEOUS SIZING MATERIAL COMPRISING BY WEIGHT, ABOUT 5%-10% BENTONITE CLAY DISPERSED IN ABOUT 95%-90% WATER AT AN APPLICATON RATE OF ABOUT 7-8 POUNDS PER 100 SQUARE FEET OF BOARD TO ONLY SURFACES OF RIGID NORMALLY POROUS CELLULOSE FIBER INSULATION BOARDS INTENDED TO BE BOARD OUTER SURFACES IN THE ROOF STRUCTURE, LAYING OVER A ROOF DECK THE SURFACE-SIZED INSULATION BOARDS IN JUXTAPOSITION TO ONE ANOTHER TO FORM A LAYER OF THERMAL INSULATION THEREON, THE PORES IN THE INTERIOR OF THE BOARDS ADJACENT THE OUTER SURFACES ONY OF THE BOARDS AND THE PORES OF THE OUTER SURFACES ONLY OF THE BOARDS RELATIE TO THE ROOF DECK FILLED WITH SIZING MATERIAL, APPLYING AN ADHESIVE LAYER OF HEAT-LIQUEFIED BITUMINOUS MATERIAL ONTO THE SIZED OUTER SURFACES OF SAID BOARDS, FROM ABOUT 90%100% OF THE BITUMINOUS MATERIAL BEING RETAINED ON THE OUTER SURFACES OF THE BOARDS DUE TO THE SIZING MATERIAL TO AVOID DIMINISHING SUBSTANTIALLY THE NORMAL THERMAL INSULATING VALUE OF SAID BOARDS BY MATERIAL DIFFUSION OF THE BITUMINOUS MATERIAL INTO THE INTEROR OF THE BOARDS, APPLYING A LAYER OF BITUMINOUS MATERIAL-SATURATED FELT ONTO THE RETAINED BITUMINOUS LAYER WHILE SAID BITUMINOUS LAYER IS IN A SOFT AND TACKY CONDITION, AND REPEATING THE STEPS OF APPLYING THE ADHESIVE BITUMINOUS LAYER AND THEN THE BITUMINOUS MATERIAL-SATURATED FELT AS AFORESAID UNTIL A PLURALITY OF ALTERNATE SUPERPOSED LAYERS OF BITUMINOUS MATERIAL AND BITUMINOUS MATERIAL-SATURATED FELT ARE APPLIED. 